Understanding the Science

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Novel endophyte technologies

Harvesting and sowing seeds are activities as old as civilisation. Innovative products and technologies add value to these ancient practices, and bring new opportunities to New Zealand livestock farmers.

Grasslanz Technology Limited is a wholly owned subsidiary of AgResearch. Grasslanz Technology develops, promotes and licences proprietary forage grasses and legumes, endophytes, and applied biotechnology to seed companies. These products are sold to farmers under licence from Grasslanz Technology by the seed companies.

Endophyte developments have been a major focus for Grasslanz Technology in recent years. Research undertaken by AgResearch (Grasslanz Technology’s parent company) in the endophyte area is world leading, and the technology has provided millions of dollars of benefit to New Zealand primary industries since the release of the novel endophyte AR1 in 2000. The research for the development of AR1 was a major team effort by mycologists, chemists, agronomists, entomologists and plant breeders. Research into the identification, understanding, testing and commercialisation of an endophyte strain takes the best part of 20 years.

The endophyte programme undertaken by Grasslanz Technology and AgResearch goes through a number of key stages. Endophytes have been isolated from grasses collected from around the world. They are identified and classified, and over the years a picture has developed as to how individual endophyte strains are related to one another. Once an endophyte strain is identified, the spectrum of chemical compounds it produces is determined, along with the impact these have on insects. Endophyte strains with a good range of insect tolerance are agronomically evaluated in a number of environments and various management styles. Endophytes that are agronomically as good or superior to standard (common toxic) endophytes are then subjected to intensive animal safety and performance testing. To be commercialised novel endophyte strains need to be superior to standard endophytes in these aspects of testing.

The final process is to develop seed production, processing, prolonged storage, and quality assurance systems. This is to ensure that the correct and a viable endophyte can be delivered to the farmer. It is important to remember that endophytes are a perishable product and a lot of care is required at the seed production, processing, and storage phases to ensure farmers actually receive the novel endophytes they purchase in their seed on their farms.

What is an endophyte?

Endophyte is a naturally occurring fungus whose complete life cycle occurs within grasses such as perennial ryegrass and tall fescue. Most New Zealand ryegrass pastures are infected with endophyte. The endophyte fungus grows between the cells of the host plant, drawing nutrients from it but in return conferring resistance to insect pests, drought tolerance, and protection from overgrazing. Such a mutually beneficial relationship is known as symbiosis. Endophytes produce chemical compounds known as alkaloids, which confer pasture pest resistance, but which can also cause animal health problems. Peramine deters in particular feeding and egg laying of Argentine Stem Weevil, but has no known effects on animal health. LolitremB deter Argentine Stem Weevil larval feeding but cause Ryegrass Staggers. Ergovaline gives resistance to Black Beetle, but causes heat stress, especially in warm humid conditions

Endophyte lifecycle

Novel endophytes

Novel endophytes are selected endophyte strains that have known and understood alkaloid chemical compound profiles. It is known what impact these compounds have on insect pests, the agronomic performance and persistence of the ryegrass and tall fescue plants, and the health and performance of animals grazing plants containing the novel endophyte strain. Novel endophytes can be incorporated into elite cultivar germplasm either by an inoculation process or by breeding and selecting with plants that contain the novel endophyte strain.

Endophyte strains commonly present in New Zealand ryegrass pastures contain the compounds lolitrems, peramines and ergovalines. The selected strain, ‘AR1’, contains peramine which gives tolerance to Argentine stem weevil and some tolerance to black beetle when plants are well established. AR1 does not contain lolitrem or ergovaline so that there is enhanced animal performance. Endo 5 contains peramine but no lolitrems. They do contain some level of ergovaline which allows for agronomic robustness, especially in areas where black beetle is an issue.

The most recent novel endophyte, ‘AR37’, does not contain lolitrems, peramine, or ergovaline, but does have a unique group of compounds called epoxy-janthitrems. Epoxy-janthitrems confer protection against a wide range of insect pests (Argentine stem weevil, black beetle, root aphid, pasture mealy bug and porina). A point of note is that AR37 controls the Black Beetle lifecycle at the adult stage rather than at the larval stage. Testing to date has shown ryegrass infected with AR37 to be more persistent and productive than pastures infected with standard endophyte, with livestock performance levels similar to AR1 and nil endophyte. While AR37 does not produce the alkaloid LolitremB it can cause ryegrass staggers in grazing livestock. In grazing trials at Lincoln the incidence of ryegrass staggers on pure ryegrass with AR37 has been less frequent and usually only half as severe as on ryegrass with standard endophyte. However, these trials have shown than spasmodically AR37 can cause serious staggers (Fletcher & Sutherland 2009: Proc NZGrassland Assn, 71: 127-33. However, to date no ryegrass staggers have been reported on any class of cattle on AR37 in trials or on commercial farms. Due to the fact that no trial work has been undertaken on deer and horses, pastures with AR37 are currently not recommended for those livestock classes or other untested species.

Novel endophytes are protected by patents
The development of novel endophytes is an expensive process over a long period of time, and they do offer farmers significant agronomic advantages and subsequent economic benefits. Due to these factors Grasslanz Technology and AgResearch have obtained Intellectual property protection in the form of patents.

What many farmers and seed growers may not be aware of, is that only companies who have a licence can produce or sell the cultivars containing novel endophytes. At the individual farmer level the patent means that seed containing novel endophytes like AR1 is protected by law. Farmers who harvest and re-sow or on-sell novel endophytes such as AR1 and AR37 to companies other than licence holders are very likely to be in breach of the patent and this may lead to prosecution under NZ law.

Choosing a Ryegrass Endophyte

Developed by Industry Endophyte Technical Committee and approved for use by NZPBRA Executive (21st September 2017)

Summary – Endophyte insect control 

These ratings are indicative and may vary slightly between cultivars.  If Argentine stem weevil or Black beetle are present at sowing, an appropriate seed treatment is recommended, to improve insect resistance during establishment.

Perennial Ryegrass, Festulolium and Italian and Short-Term (Hybrid) Ryegrass

Key to Tables
- No control
+ Low level control: Endophyte may provide a measureable   effect, but is unlikely to give any practical control.
++ Moderate control: Endophyte may provide some practical protection, with a low to moderate reduction in insect population.
+++ Good control: Endophyte markedly reduces insect damage under low to moderate insect pressures.  Damage may still occur when insect pressure is high.
++++ Very good control: Endophyte consistently reduces insect populations and keeps pasture damage to low levels, even under high insect pressure.
() Provisional result: Further results needed to support the rating.  Testing is ongoing.

 

  Argentine stem weevil Pasture mealy bug Black beetle adult Root aphid Porina Grass grub Field cricket
Diploid perennial ryegrass
AR1 ++++ ++++ + -2 - - Not tested
NEA2 +++ (++++) +++ ++ Not tested - Not tested
AR37 ++++1 ++++ +++ ++++ +++ + Not tested
SE ++++ ++++ +++ ++ + - Not tested
WE - - - - - - Not tested
Tetraploid perennial ryegrass
AR1 (+++) (++++) + -2 - - Not tested
NEA2 ++ (++++) +++ ++ Not tested - Not tested
AR37 (+++)1 (++++) +++ ++++ (+++) + Not tested
WE - - - - - - Not tested
Festulolium
U2 ++++ (++++) +++3 ++++ (++) +++ +++
Italian and short term (hybrid) ryegrass
AR1 ++ (++++) + -2 Not tested - Not tested
NEA Not tested (++++) +++ Not tested Not tested - Not tested
AR37 +++1 (++++) +++ Not tested Not tested - Not tested
WE - - - - - - Not tested
               

Notes on tables
¹ AR37 endophyte controls Argentine stem weevil larvae, but not adults.  While larvae cause most damage to pastures, adults can damage emerging grass seedlings. In Argentine stem weevil prone areas it is recommended to use treated seed for all cultivars with novel endophyte.

² AR1 plants are more susceptible to root aphid than plants without endophyte.

³ Also active against black beetle larvae

Summary – Endophyte animal safety

These ratings are indicative.  Animal performance and health can vary under different management systems between seasons.

Perennial Ryegrass and Festulolium

Key to Tables
++ Moderate animal production and health: This endophyte is known to regularly cause significant problems.
+++ Good animal production and health: This endophyte can cause problems from time to time.
++++ Very good animal production and health.

Table 1 Livestock performance – sheep & lambs

  AR1 NEA2 AR37 U2 Standard Endophyte Without Endophyte
Freedom from ryegrass staggers ++++ ++++ +++2 ++++ ++1 ++++
Animal production ++++ ++++ ++++3 ++++ ++1 ++++

Notes on Table 1
¹ Standard endophyte can cause severe ryegrass staggers, can significantly decrease lamb growth rates in summer and autumn, and significantly increase dags.

² Ryegrass containing AR37 endophyte can cause severe ryegrass staggers, but the frequency of ryegrass staggers is much lower than for ryegrass with Standard endophyte. One50 AR37 may give rise to higher instances of ryegrass staggers than other AR37 cultivars in some situations.

³ Lambs grazing ryegrass containing AR37 endophyte can have reduced LWG during periods of severe staggers.

Table 2 Livestock performance – dairy cows and beef cattle

  AR1 NEA2 AR37 U2 Standard Endophyte Without Endophyte
Freedom from ryegrass staggers ++++ ++++ ++++2 ++++ ++1 ++++
Animal production ++++ Not tested ++++3 ++++ +++1 ++++

 

Notes on Table 2

¹ Standard endophyte can cause ryegrass staggers, and has been shown to depress milksolids (MS) production through summer and autumn.

² While ryegrass staggers has not been observed on cattle and dairy cows, it could occur on rare occasions.

³ In dairy trials overall MS production from ryegrass containing AR37 endophyte is not significantly different from that with AR1. A small reduction in MS was observed over summer on ryegrass containing AR37. A contributing factor to this was the lower clover content in AR37 pastures.

 

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Collaborative research and project
management of plant technologies.
Development and licensing of plant varieties, grass endophytes and plant genes.
Protection of intellectual property through patents, trade marks and plant variety rights.
Production and sale of high quality early generation seedstock.
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